BepiColombo Project and MPO Status Comprehensive Explora1on of Planet Mercury
Joe Zender BepiColombo Deputy PS, ESA/ESTEC BepiColombo Previously: Ø Proba2 Science Coordinator, until 12/2013 Ø ProbaV, Project Office Member, until 12/2013 Ø Rosetta, (PT) LSS Support, in 2014, then Proba3, PS, from 01/2015 (tbc) Ø BC Deputy PS (PT), from 01/2014
Guide through the talk Orbit Update in 2013 Mission CDR in 2013 Development Status as of today
critical issue orbit As a consequence of gravity field measurements by MESSENGER the orbit needed to be updated MPO MMO Date (MJD2000) 8866.778 8781.630 hp (km) 480 590 ha (km) 1500 11639 T(h) 2.36 9.30 i( ) 90.0 90.0 Ω( ) 67.8 67.8 ω( ) 16.0-2.0 Table 1: Initial orbital elements of MPO and MMO in the Mercury equatorial system.
BC SWT RESOLUTION on new orbit (3 rd September 2013) On September 3, 2013, updated MPO and MMO science orbits were proposed by the project to the BC-SWT, taking into account the impact of the most recent updates of the gravitational parameters of Mercury. The SWT makes the following statements regarding the new proposed orbits of MPO (480*1500km) and MMO (590*11639km, south pole orbit insertion): Both proposed orbits are acceptable to obtain the science goals of the mission and can be used for spacecraft and science analysis. Future adaptations of the MPO orbit - in particular to secure a lower than 400km periherm altitude during the mission - shall be possible within the given constraints (thermal, delta_v). Given the current uncertainty in the gravity field of Mercury, the SWT will revisit this issue once updated MESSENGER data are available.
Periherm altitude change over time 500 450 Periherm altitude [km] 400 350 300 250 200 0 100 200 300 400 500 600 700 800 Time [days] Figure 1: MPO periherm altitude profile over 800 days.
Apoherm Altitude change over time 1750 1700 Apoherm altitude [km] 1650 1600 1550 1500 0 100 200 300 400 500 600 700 800 Time [days] Figure 2: MPO apoherm altitude profile over 800 days.
Mission Design Critical Design Review ü Board Meeting held on 15 Nov 13 CDR closed ü Number of major issues identified as below è Solar array substrate manufacturing and test è Survival Mode duration in superior conjunction è Survivability of an Aphelion eclipse in case of no MMO separation è Limited ground visibility with MPO in survival mode è Schedule leading to launch date of July 2016 è Micro Vibration acceptability è DSN network availability
Rocket: ARIANE 5 ECA Launch: July 2016 Start of Science Mission: 2024 Total Launch mass: 4200 Kg
Launch Opportunities è Launch July 2016: baseline, maintained since CDR with repeating opportunities in January 2017, July 2017 Arrival January 2024 (1 Earth, 2 Venus and 5 Mercury fly-bys)
BepiColombo Status (May 2014)
Project Status MPO PFM unit and payload final integration in Torino (Italy) ALL P/L TC sequences, required for System Function Test, have been finalized and debugged. Shipment to ESTEC planned for week 32 The MTM PFM integration for thermal and chemical propulsion hardware is on-going. Shipment to ESTEC planned for week 32 (tbc) MMO FM integration and functional verification is finished The mission and science operations preparation activities proceed as planned. CDR at Project Level planned for November 2014, including spacecraft (ESA,JAXA), payload, launcher, and ground segment
Mercury Planetary Orbiter: Status ü Harness integration complete ü All instruments integrated and IST completed; ü All AOCS units except wheels integrated and tested ü All data handling and power units integrated ü 22 N thrusters integrated and tested ü 5 N thrusters integrated and tested
Mercury Transfer Module: Status Chemical Propellant Subsystem equipment integrated Proof and leak test of high pressure section of propulsion subsystems performed System harness integration completed SEPS harness and first SEPS elements to come in July14; coupling test 2 running nominally
Contamination progress achieved Updated Model of instrument molecular contamination (MOC) established demonstrates that instrument MOC requirements achievable with implementation of protection measures è Protection measures (e.g. MLI Gap closures, Collars around apertures) under implementation è Decisions on equipment bake-out taken after justification and impact assessment è MMO/MOSIF Protective Foil agreed, detailed design under implementation Ongoing activities Cleanliness WG continues to follow-up remaining actions Test programme and materials defined for effects of UV/VUV; first tests running in ESTEC; completion expected mid 2015
Launcher ü HSS3+ low-shock fairing separation system successfully demonstrated on ATV-4 launch of Ariane 5 ü HSS3+ formally offered by Arianespace for BC è adopted as project baseline ü Retires all pending risks of re-qualification of MPO/MTM equipment Ariane 5 ECA delta-qualification in preparation
Project Status Summary ü Critical issues identified during CDR under control ü BC Schedule quite stable since 1 year ü BC TBTV test in autumn 2014 ü All P/L (replacement) models for MPO TBTV test available è Additional exchange slot for P/L end 2013 è Remaining FM P/L delivery trends critical
Spacecraft Performance
Spacecraft limitations è impact on BC science performance? 1. Science Data Return 2. Power Budget for science operations 3. Thermal Design 4. Pointing Constraints 5. Mass / reachable Science Orbit
Science data return (REQ: 1550 Gbits) The data volume per year varies 1381 Gbits (-10% for no power sharing operation and nominal sun activity) 1250 Gbits (-15% Ka-Band DL switched-off for 15 days and maximum sun activity) è Shortcomings on science return data volume have a tremendous impact on the science return of BepiColombo. Major science goals will not be achievable è problems can be solved (mitigate, compensate) by additional data download of about 300 Gbit via an additional/another ground station
Power Availability (REQ: ~160 Watt) è Outside Ground Station contact at Perihelion most instruments can be operated è During Ground Station contact at Perihelion most instruments cannot operating. This equates to a loss of about 35% of the science operation time at perihelion (~6% total). è Shortcomings on Power Availability during Perihelion Phase will impact the science return
Thermal Design issues Illustration of P/L Restriction due to Thermal Constraints
Thermal Design non-compliances è Further case studies/analysis are necessary current data base is insufficient to make proper scientific performance evaluation è Details analysis involving instrument teams/sgs of realistic scenarios is needed (to what limit can an instrument team tolerate design limit violations; what kind of margins are needed, etc è Thermal design shortcomings will lead to a major science degradation during perihelion (+/- 5-7days)
Pointing Performance Remaining non-compliances for: HRIC & STC which is driven by the AOCS performance, which is 10.9 arcsec based on worst case calculation assumption and calibration strategy BELA is non-compliant, because it can not be calibrated (provides values similar to other non-calibrated instruments) Note: Values given are worst case. For Nadir pointing results for SIMBIO-SYS are about a factor 2 better!!
critical issue Pointing Micro Vibration acceptability - Non-compliances in pointing and micro-vibration: - SIMBIO-SYS: è to be mitigated with specific calibration activities measures to determine thermal distortion effects - closed - BELA: è an improved analysis was delivered to the team and discussed and agreed - closed - ISA:è micro-vibration non-compliance under further evaluation - open
Mass Budget Negative overall MPO Mass Budget (-38kg) will lead to a degraded MPO science orbit Note: 1670km instead 1500km (-1kg = 4.5km orbit delta height) this value is a worst case prediction taken all uncertainties about outstanding units not yet delivered and accepted into account. However, it is still possible to reach nominal apoherm distance (Margin on MPO items 31.2kg). Depletion of AOGS margin would lead to improvement of ~60km) è Shortcomings on mass may be compensated
NEXT SWT Meeting SWT2014 Place: Tokyo, Japan Dates: 16-18 Sep. 2014 Organizers: Ichiro Yoshikawa (U Tokyo) Shingo Kameda (Rikkyo U)
The BepiColombo Mission http://www.esa.int/science/bepicolombo Thank you!